Patent GB-1106038-A (GB)
Title: Buttonhole mechanisms in zigzag sewing machines
IPC: D05B3/24
Filed: 1965-07-14
Abstract: 1,106,038. Sewing machines. SINGER CO. 14 July, 1965 [17 July, 1964], No. 29796/65. Heading D1G. A zig zag sewing machine comprises means for regulating the neutral position of needle swing, means for regulating the work feed, an exchangeable template formed with a buttonhole-shaped control surface and adapted to be moved step-by-step in a closed path, and a linkage responsive to movement of the template to actuate said regulating means for the production of a stitched button hole having a size related to the size of said control surface. As shown, the arm shaft 25 carries a worm wheel 28 meshing with a worm 27 driven by an electric motor. A feed advance cam 45 on shaft 25 co-operates with the forked end 46 of a pitman 47 carrying a pivoted block 48 slidable in a groove 49 in a pivoted block 50. A gear segment 52 on block 50 meshes with a gear 53 on a hollow shaft 54 turnable by means of a dial 61 for regulating the work feed. A gear 80 on shaft 25 drives a cam embraced by one end of a link 85 pivoted at 86 to a pivoted arm 87 for oscillating the latter. A groove 88 in arm 87 is slidably engaged by one end of a link 91, the other end of which is pivoted at 92 to the pivoted needle bar gate 33. A slot in link 91 is engaged by one arm of a bell crank lever 98, the other arm of which carries a handle 100 for varying the amplitude of needle swing. Arm 87 is pivoted at 93, Fig. 3, not shown, to an arm 94 pivoted at 95 to the machine frame. A bracket 101, rigid with arm 94, carries a plunger 102 having a handle 104 for swinging arm 94 and drawing plunger 102 outwardly to engage a conical surface 108 thereon with any one of three spaced notches to regulate the neutral position of needle swing. A fixed plate 121 journals a vertical shaft 129 carrying a pinion 130 and a ratchet wheel 132, Fig. 8. not shown. A lever 133, journalled on shaft 129, is biased by a spring 137 to engage a pawl 134, Fig. 8, pivoted on lever 133, with ratchet wheel 132. A stud on lever 133 co-operates with a face cam on shaft 25 for rotating shaft 129 step-by-step. Pawl 134 may be disengaged from ratchet wheel 132 by actuating the handle 149 of a bell crank lever 143 carrying an abutment 147 engaging a stud 148 on lever 133. A guide member 153, pivoted to plate 121, slidably supports a template carrier 157 having an aperture adapted to receive a buttonhole template 160 formed with an endless rack having straight sides and curved ends. Sewing of the buttonhole sides occurs when the rotating pinion 130 engages the sides of the rack. Engagement with the ends of the rack swings guide member 153 for actuating the stitch field and work feed controls to sew the ends of the buttonhole. Member 153 is connected by a link 180 to one arm of a bell crank lever 183, the other arm of which carries a pivot 184 connected by a link 186 to the work feed control, and by a link 187, Fig. 8, to stitch field control. Link 187 carries a pin 188, Fig. 8, embraced by the forked end of one arm of a bell crank lever 194, the other arm of which carries a handle 196, whereby pin 188 may be shifted into or out of engagement with a slot 189, Fig. 8, in arm 94. Link 186 is connected by a linkage 211, 212, 215, 217, 219 to one end of a shaft 221 journalled in shaft 54. The other end of shaft 221 is formed with an elongated transverse aperture 222 receiving a pin 223 fixed diametrically to a dial 224. Shaft 221 is also formed with an elongated transverse aperture 225 receiving a pin 226 asymmetrically fixed in a pair of arms 227. Pin 226 is biased against an adjustable stop screw 229 by a spring 230. Arms 227 may be turned into engagement with dial 224 to bias the latter against dial 61 for coupling together shaft 54 and 221, uncoupling being effected by turning arms 227 away from dial 224. A plunger 241 carried by dial 224 has an eccentric end 243 which is engaged with a radial groove 240 in dial 61 when the feed setting is substantially zero and pinion 130 engages the middle of a moved end of a template rack. Fine adjustment may then be effected by turning plunger 241, to ensure correct positioning of feed reversal, before coupling shaft 221 to shaft 54.